This invention relates to a radome aberration correcting system, particularly, although not exclusively, for use in a target tracking missile.
It is known that the effect of a radome between a steerable antenna and a target gives rise to errors in the derivation of the target line of sight. It has previously been proposed to correct such aberration by adjusting the thickness of the radome locally for a range of target directions relative to the radome. Such a procedure is very tedious and time consuming since the radome is commonly made of refractory ceramic material which has to be ground to adjust its contour.
Another proposal for correcting radome aberration is- to-store the line of sight errors for a range of target directions and to make the appropriate correction according to the apparent line of sight.
Both of these proposals however are practicable only in a single frequency, or at least very narrow band, system. In the case of the mechanical adjustment by local grinding, it can even happen that the adjustments made for one particular operating frequency actually make matters worse at a slightly different frequency.
It might be thought that in the case of the error storage correction method, it would be simply a matter of storing a greater range of errors, i.e. repeat the stored data appropriate to one particular frequency for each of a range of frequency values. In practice it is found that this is not a practicable solution however because of the vast amount of storage necessary.